/*

This file is part of the iText (R) project.
Copyright (c) 1998-2020 iText Group NV
Authors: Bruno Lowagie, Paulo Soares, et al.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License version 3
as published by the Free Software Foundation with the addition of the
following permission added to Section 15 as permitted in Section 7(a):
FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
OF THIRD PARTY RIGHTS

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program; if not, see http://www.gnu.org/licenses or write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA, 02110-1301 USA, or download the license from the following URL:
http://itextpdf.com/terms-of-use/

The interactive user interfaces in modified source and object code versions
of this program must display Appropriate Legal Notices, as required under
Section 5 of the GNU Affero General Public License.

In accordance with Section 7(b) of the GNU Affero General Public License,
a covered work must retain the producer line in every PDF that is created
or manipulated using iText.

You can be released from the requirements of the license by purchasing
a commercial license. Buying such a license is mandatory as soon as you
develop commercial activities involving the iText software without
disclosing the source code of your own applications.
These activities include: offering paid services to customers as an ASP,
serving PDFs on the fly in a web application, shipping iText with a closed
source product.

For more information, please contact iText Software Corp. at this
address: sales@itextpdf.com
*/
using System;
using System.Collections.Generic;
using iText.IO.Util;

namespace iText.IO.Font {
    public class PdfEncodings {
        //-Encodings--------------------------------------------------------------------------------------------------------
        /// <summary>The Unicode encoding with horizontal writing.</summary>
        public const String IDENTITY_H = "Identity-H";

        /// <summary>The Unicode encoding with vertical writing.</summary>
        public const String IDENTITY_V = "Identity-V";

        /// <summary>A possible encoding.</summary>
        public const String CP1250 = "Windows-1250";

        /// <summary>A possible encoding.</summary>
        public const String CP1252 = "Windows-1252";

        /// <summary>A possible encoding.</summary>
        public const String CP1253 = "Windows-1253";

        /// <summary>A possible encoding.</summary>
        public const String CP1257 = "Windows-1257";

        /// <summary>A possible encoding.</summary>
        public const String WINANSI = "Windows-1252";

        /// <summary>A possible encoding.</summary>
        public const String MACROMAN = "MacRoman";

        /// <summary>A possible encoding.</summary>
        public const String SYMBOL = "Symbol";

        /// <summary>A possible encoding.</summary>
        public const String ZAPFDINGBATS = "ZapfDingbats";

        /// <summary>This is the encoding to be used to output text in Unicode.</summary>
        public const String UNICODE_BIG = "UnicodeBig";

        /// <summary>This is the encoding to be used to output text for Identity-H/V CMaps.</summary>
        public const String UNICODE_BIG_UNMARKED = "UnicodeBigUnmarked";

        /// <summary>
        /// This is the default encoding to be used for converting Strings into
        /// bytes and vice versa.
        /// </summary>
        /// <remarks>
        /// This is the default encoding to be used for converting Strings into
        /// bytes and vice versa. The default encoding is PDF_DOC_ENCODING.
        /// </remarks>
        public const String PDF_DOC_ENCODING = "PDF";

        public const String UTF8 = "UTF-8";

        private const String EMPTY_STRING = "";

        private static readonly char[] winansiByteToChar = new char[] { (char)0, (char)1, (char)2, (char)3, (char)
            4, (char)5, (char)6, (char)7, (char)8, (char)9, (char)10, (char)11, (char)12, (char)13, (char)14, (char
            )15, (char)16, (char)17, (char)18, (char)19, (char)20, (char)21, (char)22, (char)23, (char)24, (char)25
            , (char)26, (char)27, (char)28, (char)29, (char)30, (char)31, (char)32, (char)33, (char)34, (char)35, 
            (char)36, (char)37, (char)38, (char)39, (char)40, (char)41, (char)42, (char)43, (char)44, (char)45, (char
            )46, (char)47, (char)48, (char)49, (char)50, (char)51, (char)52, (char)53, (char)54, (char)55, (char)56
            , (char)57, (char)58, (char)59, (char)60, (char)61, (char)62, (char)63, (char)64, (char)65, (char)66, 
            (char)67, (char)68, (char)69, (char)70, (char)71, (char)72, (char)73, (char)74, (char)75, (char)76, (char
            )77, (char)78, (char)79, (char)80, (char)81, (char)82, (char)83, (char)84, (char)85, (char)86, (char)87
            , (char)88, (char)89, (char)90, (char)91, (char)92, (char)93, (char)94, (char)95, (char)96, (char)97, 
            (char)98, (char)99, (char)100, (char)101, (char)102, (char)103, (char)104, (char)105, (char)106, (char
            )107, (char)108, (char)109, (char)110, (char)111, (char)112, (char)113, (char)114, (char)115, (char)116
            , (char)117, (char)118, (char)119, (char)120, (char)121, (char)122, (char)123, (char)124, (char)125, (
            char)126, (char)127, (char)8364, (char)65533, (char)8218, (char)402, (char)8222, (char)8230, (char)8224
            , (char)8225, (char)710, (char)8240, (char)352, (char)8249, (char)338, (char)65533, (char)381, (char)65533
            , (char)65533, (char)8216, (char)8217, (char)8220, (char)8221, (char)8226, (char)8211, (char)8212, (char
            )732, (char)8482, (char)353, (char)8250, (char)339, (char)65533, (char)382, (char)376, (char)160, (char
            )161, (char)162, (char)163, (char)164, (char)165, (char)166, (char)167, (char)168, (char)169, (char)170
            , (char)171, (char)172, (char)173, (char)174, (char)175, (char)176, (char)177, (char)178, (char)179, (
            char)180, (char)181, (char)182, (char)183, (char)184, (char)185, (char)186, (char)187, (char)188, (char
            )189, (char)190, (char)191, (char)192, (char)193, (char)194, (char)195, (char)196, (char)197, (char)198
            , (char)199, (char)200, (char)201, (char)202, (char)203, (char)204, (char)205, (char)206, (char)207, (
            char)208, (char)209, (char)210, (char)211, (char)212, (char)213, (char)214, (char)215, (char)216, (char
            )217, (char)218, (char)219, (char)220, (char)221, (char)222, (char)223, (char)224, (char)225, (char)226
            , (char)227, (char)228, (char)229, (char)230, (char)231, (char)232, (char)233, (char)234, (char)235, (
            char)236, (char)237, (char)238, (char)239, (char)240, (char)241, (char)242, (char)243, (char)244, (char
            )245, (char)246, (char)247, (char)248, (char)249, (char)250, (char)251, (char)252, (char)253, (char)254
            , (char)255 };

        private static readonly char[] pdfEncodingByteToChar = new char[] { (char)0, (char)1, (char)2, (char)3, (char
            )4, (char)5, (char)6, (char)7, (char)8, (char)9, (char)10, (char)11, (char)12, (char)13, (char)14, (char
            )15, (char)16, (char)17, (char)18, (char)19, (char)20, (char)21, (char)22, (char)23, (char)24, (char)25
            , (char)26, (char)27, (char)28, (char)29, (char)30, (char)31, (char)32, (char)33, (char)34, (char)35, 
            (char)36, (char)37, (char)38, (char)39, (char)40, (char)41, (char)42, (char)43, (char)44, (char)45, (char
            )46, (char)47, (char)48, (char)49, (char)50, (char)51, (char)52, (char)53, (char)54, (char)55, (char)56
            , (char)57, (char)58, (char)59, (char)60, (char)61, (char)62, (char)63, (char)64, (char)65, (char)66, 
            (char)67, (char)68, (char)69, (char)70, (char)71, (char)72, (char)73, (char)74, (char)75, (char)76, (char
            )77, (char)78, (char)79, (char)80, (char)81, (char)82, (char)83, (char)84, (char)85, (char)86, (char)87
            , (char)88, (char)89, (char)90, (char)91, (char)92, (char)93, (char)94, (char)95, (char)96, (char)97, 
            (char)98, (char)99, (char)100, (char)101, (char)102, (char)103, (char)104, (char)105, (char)106, (char
            )107, (char)108, (char)109, (char)110, (char)111, (char)112, (char)113, (char)114, (char)115, (char)116
            , (char)117, (char)118, (char)119, (char)120, (char)121, (char)122, (char)123, (char)124, (char)125, (
            char)126, (char)127, (char)0x2022, (char)0x2020, (char)0x2021, (char)0x2026, (char)0x2014, (char)0x2013
            , (char)0x0192, (char)0x2044, (char)0x2039, (char)0x203a, (char)0x2212, (char)0x2030, (char)0x201e, (char
            )0x201c, (char)0x201d, (char)0x2018, (char)0x2019, (char)0x201a, (char)0x2122, (char)0xfb01, (char)0xfb02
            , (char)0x0141, (char)0x0152, (char)0x0160, (char)0x0178, (char)0x017d, (char)0x0131, (char)0x0142, (char
            )0x0153, (char)0x0161, (char)0x017e, (char)65533, (char)0x20ac, (char)161, (char)162, (char)163, (char
            )164, (char)165, (char)166, (char)167, (char)168, (char)169, (char)170, (char)171, (char)172, (char)173
            , (char)174, (char)175, (char)176, (char)177, (char)178, (char)179, (char)180, (char)181, (char)182, (
            char)183, (char)184, (char)185, (char)186, (char)187, (char)188, (char)189, (char)190, (char)191, (char
            )192, (char)193, (char)194, (char)195, (char)196, (char)197, (char)198, (char)199, (char)200, (char)201
            , (char)202, (char)203, (char)204, (char)205, (char)206, (char)207, (char)208, (char)209, (char)210, (
            char)211, (char)212, (char)213, (char)214, (char)215, (char)216, (char)217, (char)218, (char)219, (char
            )220, (char)221, (char)222, (char)223, (char)224, (char)225, (char)226, (char)227, (char)228, (char)229
            , (char)230, (char)231, (char)232, (char)233, (char)234, (char)235, (char)236, (char)237, (char)238, (
            char)239, (char)240, (char)241, (char)242, (char)243, (char)244, (char)245, (char)246, (char)247, (char
            )248, (char)249, (char)250, (char)251, (char)252, (char)253, (char)254, (char)255 };

        internal static readonly int[] standardEncoding = new int[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 32, 33, 34, 35, 36, 37, 38, 8217, 40, 41, 42, 43, 44
            , 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 
            70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95
            , 8216, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116
            , 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 161, 162, 163, 8260, 165, 402, 167, 164, 39, 8220, 
            171, 8249, 8250, 64257, 64258, 0, 8211, 8224, 8225, 183, 0, 182, 8226, 8218, 8222, 8221, 187, 8230, 8240
            , 0, 191, 0, 96, 180, 710, 732, 175, 728, 729, 168, 0, 730, 184, 0, 733, 731, 711, 8212, 0, 0, 0, 0, 0
            , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 198, 0, 170, 0, 0, 0, 0, 321, 216, 338, 186, 0, 0, 0, 0, 0, 230, 0, 
            0, 0, 305, 0, 0, 322, 248, 339, 223, 0, 0, 0, 0 };

        private static readonly IntHashtable winansi = new IntHashtable();

        private static readonly IntHashtable pdfEncoding = new IntHashtable();

        private static readonly IDictionary<String, IExtraEncoding> extraEncodings = new Dictionary<String, IExtraEncoding
            >();

        static PdfEncodings() {
            for (int k = 128; k < 161; ++k) {
                char c = winansiByteToChar[k];
                if (c != 65533) {
                    winansi.Put((int)c, k);
                }
            }
            for (int k = 128; k < 161; ++k) {
                char c = pdfEncodingByteToChar[k];
                if (c != 65533) {
                    pdfEncoding.Put((int)c, k);
                }
            }
            AddExtraEncoding("Wingdings", new PdfEncodings.WingdingsConversion());
            AddExtraEncoding("Symbol", new PdfEncodings.SymbolConversion(true));
            AddExtraEncoding("ZapfDingbats", new PdfEncodings.SymbolConversion(false));
            AddExtraEncoding("SymbolTT", new PdfEncodings.SymbolTTConversion());
            AddExtraEncoding("Cp437", new PdfEncodings.Cp437Conversion());
        }

        /// <summary>
        /// Converts a
        /// <c>String</c>
        /// to a
        /// <c>byte</c>
        /// array according
        /// to the font's encoding.
        /// </summary>
        /// <param name="encoding">the encoding</param>
        /// <param name="text">
        /// the
        /// <c>String</c>
        /// to be converted
        /// </param>
        /// <returns>
        /// an array of
        /// <c>byte</c>
        /// representing the conversion according to the font's encoding
        /// </returns>
        public static byte[] ConvertToBytes(String text, String encoding) {
            if (text == null) {
                return new byte[0];
            }
            if (encoding == null || encoding.Length == 0) {
                int len = text.Length;
                byte[] b = new byte[len];
                for (int k = 0; k < len; ++k) {
                    b[k] = (byte)text[k];
                }
                return b;
            }
            IExtraEncoding extra = extraEncodings.Get(encoding.ToLowerInvariant());
            if (extra != null) {
                byte[] b = extra.CharToByte(text, encoding);
                if (b != null) {
                    return b;
                }
            }
            IntHashtable hash = null;
            if (encoding.Equals(WINANSI)) {
                hash = winansi;
            }
            else {
                if (encoding.Equals(PDF_DOC_ENCODING)) {
                    hash = pdfEncoding;
                }
            }
            if (hash != null) {
                char[] cc = text.ToCharArray();
                int len = cc.Length;
                int ptr = 0;
                byte[] b = new byte[len];
                int c;
                for (int k = 0; k < len; ++k) {
                    char ch = cc[k];
                    if (ch < 128 || ch > 160 && ch <= 255) {
                        c = ch;
                    }
                    else {
                        c = hash.Get((int)ch);
                    }
                    if (c != 0) {
                        b[ptr++] = (byte)c;
                    }
                }
                if (ptr == len) {
                    return b;
                }
                byte[] b2 = new byte[ptr];
                Array.Copy(b, 0, b2, 0, ptr);
                return b2;
            }
            try {
                return EncodingUtil.ConvertToBytes(text.ToCharArray(), encoding);
            }
            catch (System.IO.IOException e) {
                throw new iText.IO.IOException(iText.IO.IOException.CharacterCodeException, e);
            }
        }

        /// <summary>
        /// Converts a
        /// <c>String</c>
        /// to a
        /// <c>byte</c>
        /// array according
        /// to the font's encoding.
        /// </summary>
        /// <param name="encoding">the encoding</param>
        /// <param name="ch">
        /// the
        /// <c>char</c>
        /// to be converted
        /// </param>
        /// <returns>
        /// an array of
        /// <c>byte</c>
        /// representing the conversion according to the font's encoding
        /// </returns>
        public static byte[] ConvertToBytes(char ch, String encoding) {
            if (encoding == null || encoding.Length == 0) {
                return new byte[] { (byte)ch };
            }
            IntHashtable hash = null;
            if (encoding.Equals(WINANSI)) {
                hash = winansi;
            }
            else {
                if (encoding.Equals(PDF_DOC_ENCODING)) {
                    hash = pdfEncoding;
                }
            }
            if (hash != null) {
                int c;
                if (ch < 128 || ch > 160 && ch <= 255) {
                    c = ch;
                }
                else {
                    c = hash.Get((int)ch);
                }
                if (c != 0) {
                    return new byte[] { (byte)c };
                }
                else {
                    return new byte[0];
                }
            }
            try {
                return EncodingUtil.ConvertToBytes(new char[] { ch }, encoding);
            }
            catch (System.IO.IOException e) {
                throw new iText.IO.IOException(iText.IO.IOException.CharacterCodeException, e);
            }
        }

        /// <summary>
        /// Converts a
        /// <c>byte</c>
        /// array to a
        /// <c>String</c>
        /// according
        /// to the some encoding.
        /// </summary>
        /// <param name="bytes">the bytes to convert</param>
        /// <param name="encoding">the encoding</param>
        /// <returns>
        /// the converted
        /// <c>String</c>
        /// </returns>
        public static String ConvertToString(byte[] bytes, String encoding) {
            if (bytes == null) {
                return EMPTY_STRING;
            }
            if (encoding == null || encoding.Length == 0) {
                char[] c = new char[bytes.Length];
                for (int k = 0; k < bytes.Length; ++k) {
                    c[k] = (char)(bytes[k] & 0xff);
                }
                return new String(c);
            }
            IExtraEncoding extra = extraEncodings.Get(encoding.ToLowerInvariant());
            if (extra != null) {
                String text = extra.ByteToChar(bytes, encoding);
                if (text != null) {
                    return text;
                }
            }
            char[] ch = null;
            if (encoding.Equals(WINANSI)) {
                ch = winansiByteToChar;
            }
            else {
                if (encoding.Equals(PDF_DOC_ENCODING)) {
                    ch = pdfEncodingByteToChar;
                }
            }
            if (ch != null) {
                int len = bytes.Length;
                char[] c = new char[len];
                for (int k = 0; k < len; ++k) {
                    c[k] = ch[bytes[k] & 0xff];
                }
                return new String(c);
            }
            try {
                return EncodingUtil.ConvertToString(bytes, encoding);
            }
            catch (ArgumentException e) {
                throw new iText.IO.IOException(iText.IO.IOException.UnsupportedEncodingException, e);
            }
        }

        /// <summary>
        /// Checks is
        /// <paramref name="text"/>
        /// only has PDF_DOC_ENCODING characters.
        /// </summary>
        /// <param name="text">
        /// the
        /// <c>String</c>
        /// to test
        /// </param>
        /// <returns>
        /// 
        /// <see langword="true"/>
        /// if only PDF_DOC_ENCODING characters are present
        /// </returns>
        public static bool IsPdfDocEncoding(String text) {
            if (text == null) {
                return true;
            }
            int len = text.Length;
            for (int k = 0; k < len; k++) {
                char ch = text[k];
                if (ch < 128 || ch > 160 && ch <= 255) {
                    continue;
                }
                if (!pdfEncoding.ContainsKey((int)ch)) {
                    return false;
                }
            }
            return true;
        }

        /// <summary>Adds an extra encoding.</summary>
        /// <param name="name">the name of the encoding. The encoding recognition is case insensitive</param>
        /// <param name="enc">the conversion class</param>
        public static void AddExtraEncoding(String name, IExtraEncoding enc) {
            lock (extraEncodings) {
                extraEncodings.Put(name.ToLowerInvariant(), enc);
            }
        }

        private class WingdingsConversion : IExtraEncoding {
            public virtual byte[] CharToByte(char char1, String encoding) {
                if (char1 == ' ') {
                    return new byte[] { (byte)char1 };
                }
                else {
                    if (char1 >= '\u2701' && char1 <= '\u27BE') {
                        byte v = table[char1 - 0x2700];
                        if (v != 0) {
                            return new byte[] { v };
                        }
                    }
                }
                return new byte[0];
            }

            public virtual byte[] CharToByte(String text, String encoding) {
                char[] cc = text.ToCharArray();
                byte[] b = new byte[cc.Length];
                int ptr = 0;
                int len = cc.Length;
                for (int k = 0; k < len; ++k) {
                    char c = cc[k];
                    if (c == ' ') {
                        b[ptr++] = (byte)c;
                    }
                    else {
                        if (c >= '\u2701' && c <= '\u27BE') {
                            byte v = table[c - 0x2700];
                            if (v != 0) {
                                b[ptr++] = v;
                            }
                        }
                    }
                }
                if (ptr == len) {
                    return b;
                }
                byte[] b2 = new byte[ptr];
                Array.Copy(b, 0, b2, 0, ptr);
                return b2;
            }

            public virtual String ByteToChar(byte[] b, String encoding) {
                return null;
            }

            private static readonly byte[] table = new byte[] { (byte)0x00, (byte)0x23, (byte)0x22, (byte)0x00, (byte)
                0x00, (byte)0x00, (byte)0x29, (byte)0x3e, (byte)0x51, (byte)0x2a, (byte)0x00, (byte)0x00, (byte)0x41, 
                (byte)0x3f, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0xfc, (byte)0x00, (byte)
                0x00, (byte)0x00, (byte)0xfb, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, 
                (byte)0x56, (byte)0x00, (byte)0x58, (byte)0x59, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)
                0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0xb5, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, 
                (byte)0x00, (byte)0xb6, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0xad, (byte)0xaf, (byte)0xac, (byte)
                0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x7c, 
                (byte)0x7b, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x54, (byte)0x00, (byte)0x00, (byte)0x00, (byte)
                0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0xa6, (byte)0x00, (byte)0x00, (byte)0x00, 
                (byte)0x71, (byte)0x72, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x75, (byte)0x00, (byte)0x00, (byte)
                0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x7d, (byte)0x7e, (byte)0x00, (byte)0x00, (byte)0x00, 
                (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)
                0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, 
                (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x8c, (byte)0x8d, (byte)0x8e, (byte)0x8f, (byte)0x90, (byte)
                0x91, (byte)0x92, (byte)0x93, (byte)0x94, (byte)0x95, (byte)0x81, (byte)0x82, (byte)0x83, (byte)0x84, 
                (byte)0x85, (byte)0x86, (byte)0x87, (byte)0x88, (byte)0x89, (byte)0x8a, (byte)0x8c, (byte)0x8d, (byte)
                0x8e, (byte)0x8f, (byte)0x90, (byte)0x91, (byte)0x92, (byte)0x93, (byte)0x94, (byte)0x95, (byte)0xe8, 
                (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)
                0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0xe8, (byte)0xd8, (byte)0x00, (byte)0x00, (byte)0xc4, 
                (byte)0xc6, (byte)0x00, (byte)0x00, (byte)0xf0, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)
                0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0xdc, (byte)0x00, (byte)0x00, (byte)0x00, 
                (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00 };
        }

        private class Cp437Conversion : IExtraEncoding {
            private static IntHashtable c2b = new IntHashtable();

            public virtual byte[] CharToByte(String text, String encoding) {
                char[] cc = text.ToCharArray();
                byte[] b = new byte[cc.Length];
                int ptr = 0;
                int len = cc.Length;
                for (int k = 0; k < len; ++k) {
                    char c = cc[k];
                    if (c < 128) {
                        b[ptr++] = (byte)c;
                    }
                    else {
                        byte v = (byte)c2b.Get(c);
                        if (v != 0) {
                            b[ptr++] = v;
                        }
                    }
                }
                if (ptr == len) {
                    return b;
                }
                byte[] b2 = new byte[ptr];
                Array.Copy(b, 0, b2, 0, ptr);
                return b2;
            }

            public virtual byte[] CharToByte(char char1, String encoding) {
                if (char1 < 128) {
                    return new byte[] { (byte)char1 };
                }
                else {
                    byte v = (byte)c2b.Get(char1);
                    if (v != 0) {
                        return new byte[] { v };
                    }
                    else {
                        return new byte[0];
                    }
                }
            }

            public virtual String ByteToChar(byte[] b, String encoding) {
                int len = b.Length;
                char[] cc = new char[len];
                int ptr = 0;
                for (int k = 0; k < len; ++k) {
                    int c = b[k] & 0xff;
                    if (c < ' ') {
                        continue;
                    }
                    if (c < 128) {
                        cc[ptr++] = (char)c;
                    }
                    else {
                        char v = table[c - 128];
                        cc[ptr++] = v;
                    }
                }
                return new String(cc, 0, ptr);
            }

            private static readonly char[] table = new char[] { '\u00C7', '\u00FC', '\u00E9', '\u00E2', '\u00E4', '\u00E0'
                , '\u00E5', '\u00E7', '\u00EA', '\u00EB', '\u00E8', '\u00EF', '\u00EE', '\u00EC', '\u00C4', '\u00C5', 
                '\u00C9', '\u00E6', '\u00C6', '\u00F4', '\u00F6', '\u00F2', '\u00FB', '\u00F9', '\u00FF', '\u00D6', '\u00DC'
                , '\u00A2', '\u00A3', '\u00A5', '\u20A7', '\u0192', '\u00E1', '\u00ED', '\u00F3', '\u00FA', '\u00F1', 
                '\u00D1', '\u00AA', '\u00BA', '\u00BF', '\u2310', '\u00AC', '\u00BD', '\u00BC', '\u00A1', '\u00AB', '\u00BB'
                , '\u2591', '\u2592', '\u2593', '\u2502', '\u2524', '\u2561', '\u2562', '\u2556', '\u2555', '\u2563', 
                '\u2551', '\u2557', '\u255D', '\u255C', '\u255B', '\u2510', '\u2514', '\u2534', '\u252C', '\u251C', '\u2500'
                , '\u253C', '\u255E', '\u255F', '\u255A', '\u2554', '\u2569', '\u2566', '\u2560', '\u2550', '\u256C', 
                '\u2567', '\u2568', '\u2564', '\u2565', '\u2559', '\u2558', '\u2552', '\u2553', '\u256B', '\u256A', '\u2518'
                , '\u250C', '\u2588', '\u2584', '\u258C', '\u2590', '\u2580', '\u03B1', '\u00DF', '\u0393', '\u03C0', 
                '\u03A3', '\u03C3', '\u00B5', '\u03C4', '\u03A6', '\u0398', '\u03A9', '\u03B4', '\u221E', '\u03C6', '\u03B5'
                , '\u2229', '\u2261', '\u00B1', '\u2265', '\u2264', '\u2320', '\u2321', '\u00F7', '\u2248', '\u00B0', 
                '\u2219', '\u00B7', '\u221A', '\u207F', '\u00B2', '\u25A0', '\u00A0' };

            static Cp437Conversion() {
                for (int k = 0; k < table.Length; ++k) {
                    c2b.Put(table[k], k + 128);
                }
            }
        }

        private class SymbolConversion : IExtraEncoding {
            private static readonly IntHashtable t1 = new IntHashtable();

            private static readonly IntHashtable t2 = new IntHashtable();

            private IntHashtable translation;

            private readonly char[] byteToChar;

            internal SymbolConversion(bool symbol) {
                if (symbol) {
                    translation = t1;
                    byteToChar = table1;
                }
                else {
                    translation = t2;
                    byteToChar = table2;
                }
            }

            public virtual byte[] CharToByte(String text, String encoding) {
                char[] cc = text.ToCharArray();
                byte[] b = new byte[cc.Length];
                int ptr = 0;
                int len = cc.Length;
                for (int k = 0; k < len; ++k) {
                    char c = cc[k];
                    byte v = (byte)translation.Get(c);
                    if (v != 0) {
                        b[ptr++] = v;
                    }
                }
                if (ptr == len) {
                    return b;
                }
                byte[] b2 = new byte[ptr];
                Array.Copy(b, 0, b2, 0, ptr);
                return b2;
            }

            public virtual byte[] CharToByte(char char1, String encoding) {
                byte v = (byte)translation.Get(char1);
                if (v != 0) {
                    return new byte[] { v };
                }
                else {
                    return new byte[0];
                }
            }

            public virtual String ByteToChar(byte[] b, String encoding) {
                int len = b.Length;
                char[] cc = new char[len];
                int ptr = 0;
                for (int k = 0; k < len; ++k) {
                    int c = b[k] & 0xff;
                    char v = byteToChar[c];
                    cc[ptr++] = v;
                }
                return new String(cc, 0, ptr);
            }

            private static readonly char[] table1 = new char[] { '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', 
                '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', 
                '\0', '\0', '\0', '\0', '\0', '\0', ' ', '!', '\u2200', '#', '\u2203', '%', '&', '\u220b', '(', ')', '*'
                , '+', ',', '-', '.', '/', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ':', ';', '<', '=', '>', 
                '?', '\u2245', '\u0391', '\u0392', '\u03a7', '\u0394', '\u0395', '\u03a6', '\u0393', '\u0397', '\u0399'
                , '\u03d1', '\u039a', '\u039b', '\u039c', '\u039d', '\u039f', '\u03a0', '\u0398', '\u03a1', '\u03a3', 
                '\u03a4', '\u03a5', '\u03c2', '\u03a9', '\u039e', '\u03a8', '\u0396', '[', '\u2234', ']', '\u22a5', '_'
                , '\u0305', '\u03b1', '\u03b2', '\u03c7', '\u03b4', '\u03b5', '\u03d5', '\u03b3', '\u03b7', '\u03b9', 
                '\u03c6', '\u03ba', '\u03bb', '\u03bc', '\u03bd', '\u03bf', '\u03c0', '\u03b8', '\u03c1', '\u03c3', '\u03c4'
                , '\u03c5', '\u03d6', '\u03c9', '\u03be', '\u03c8', '\u03b6', '{', '|', '}', '~', '\0', '\0', '\0', '\0'
                , '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0'
                , '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\u20ac', '\u03d2', '\u2032'
                , '\u2264', '\u2044', '\u221e', '\u0192', '\u2663', '\u2666', '\u2665', '\u2660', '\u2194', '\u2190', 
                '\u2191', '\u2192', '\u2193', '\u00b0', '\u00b1', '\u2033', '\u2265', '\u00d7', '\u221d', '\u2202', '\u2022'
                , '\u00f7', '\u2260', '\u2261', '\u2248', '\u2026', '\u2502', '\u2500', '\u21b5', '\u2135', '\u2111', 
                '\u211c', '\u2118', '\u2297', '\u2295', '\u2205', '\u2229', '\u222a', '\u2283', '\u2287', '\u2284', '\u2282'
                , '\u2286', '\u2208', '\u2209', '\u2220', '\u2207', '\u00ae', '\u00a9', '\u2122', '\u220f', '\u221a', 
                '\u22c5', '\u00ac', '\u2227', '\u2228', '\u21d4', '\u21d0', '\u21d1', '\u21d2', '\u21d3', '\u25ca', '\u2329'
                , '\0', '\0', '\0', '\u2211', '\u239b', '\u239c', '\u239d', '\u23a1', '\u23a2', '\u23a3', '\u23a7', '\u23a8'
                , '\u23a9', '\u23aa', '\0', '\u232a', '\u222b', '\u2320', '\u23ae', '\u2321', '\u239e', '\u239f', '\u23a0'
                , '\u23a4', '\u23a5', '\u23a6', '\u23ab', '\u23ac', '\u23ad', '\0' };

            private static readonly char[] table2 = new char[] { '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', 
                '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', 
                '\0', '\0', '\0', '\0', '\0', '\0', '\u0020', '\u2701', '\u2702', '\u2703', '\u2704', '\u260e', '\u2706'
                , '\u2707', '\u2708', '\u2709', '\u261b', '\u261e', '\u270C', '\u270D', '\u270E', '\u270F', '\u2710', 
                '\u2711', '\u2712', '\u2713', '\u2714', '\u2715', '\u2716', '\u2717', '\u2718', '\u2719', '\u271A', '\u271B'
                , '\u271C', '\u271D', '\u271E', '\u271F', '\u2720', '\u2721', '\u2722', '\u2723', '\u2724', '\u2725', 
                '\u2726', '\u2727', '\u2605', '\u2729', '\u272A', '\u272B', '\u272C', '\u272D', '\u272E', '\u272F', '\u2730'
                , '\u2731', '\u2732', '\u2733', '\u2734', '\u2735', '\u2736', '\u2737', '\u2738', '\u2739', '\u273A', 
                '\u273B', '\u273C', '\u273D', '\u273E', '\u273F', '\u2740', '\u2741', '\u2742', '\u2743', '\u2744', '\u2745'
                , '\u2746', '\u2747', '\u2748', '\u2749', '\u274A', '\u274B', '\u25cf', '\u274D', '\u25a0', '\u274F', 
                '\u2750', '\u2751', '\u2752', '\u25b2', '\u25bc', '\u25c6', '\u2756', '\u25d7', '\u2758', '\u2759', '\u275A'
                , '\u275B', '\u275C', '\u275D', '\u275E', '\u0000', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0'
                , '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0'
                , '\0', '\0', '\0', '\0', '\0', '\0', '\u0000', '\u2761', '\u2762', '\u2763', '\u2764', '\u2765', '\u2766'
                , '\u2767', '\u2663', '\u2666', '\u2665', '\u2660', '\u2460', '\u2461', '\u2462', '\u2463', '\u2464', 
                '\u2465', '\u2466', '\u2467', '\u2468', '\u2469', '\u2776', '\u2777', '\u2778', '\u2779', '\u277A', '\u277B'
                , '\u277C', '\u277D', '\u277E', '\u277F', '\u2780', '\u2781', '\u2782', '\u2783', '\u2784', '\u2785', 
                '\u2786', '\u2787', '\u2788', '\u2789', '\u278A', '\u278B', '\u278C', '\u278D', '\u278E', '\u278F', '\u2790'
                , '\u2791', '\u2792', '\u2793', '\u2794', '\u2192', '\u2194', '\u2195', '\u2798', '\u2799', '\u279A', 
                '\u279B', '\u279C', '\u279D', '\u279E', '\u279F', '\u27A0', '\u27A1', '\u27A2', '\u27A3', '\u27A4', '\u27A5'
                , '\u27A6', '\u27A7', '\u27A8', '\u27A9', '\u27AA', '\u27AB', '\u27AC', '\u27AD', '\u27AE', '\u27AF', 
                '\u0000', '\u27B1', '\u27B2', '\u27B3', '\u27B4', '\u27B5', '\u27B6', '\u27B7', '\u27B8', '\u27B9', '\u27BA'
                , '\u27BB', '\u27BC', '\u27BD', '\u27BE', '\u0000' };

            static SymbolConversion() {
                for (int k = 0; k < 256; ++k) {
                    int v = table1[k];
                    if (v != 0) {
                        t1.Put(v, k);
                    }
                }
                for (int k = 0; k < 256; ++k) {
                    int v = table2[k];
                    if (v != 0) {
                        t2.Put(v, k);
                    }
                }
            }
        }

        private class SymbolTTConversion : IExtraEncoding {
            public virtual byte[] CharToByte(char char1, String encoding) {
                if ((char1 & 0xff00) == 0 || (char1 & 0xff00) == 0xf000) {
                    return new byte[] { (byte)char1 };
                }
                else {
                    return new byte[0];
                }
            }

            public virtual byte[] CharToByte(String text, String encoding) {
                char[] ch = text.ToCharArray();
                byte[] b = new byte[ch.Length];
                int ptr = 0;
                int len = ch.Length;
                for (int k = 0; k < len; ++k) {
                    char c = ch[k];
                    if ((c & 0xff00) == 0 || (c & 0xff00) == 0xf000) {
                        b[ptr++] = (byte)c;
                    }
                }
                if (ptr == len) {
                    return b;
                }
                byte[] b2 = new byte[ptr];
                Array.Copy(b, 0, b2, 0, ptr);
                return b2;
            }

            public virtual String ByteToChar(byte[] b, String encoding) {
                return null;
            }
        }
    }
}
